I can't figure out the location of the 50°, 100° and 140° angles
I am guessing that they represent the corresponding arclengths?
e.g. arc BG would be 50/360 of the circumference?
Anyway, it is past midnight, if nobody works at it I will look at it again in the morning.
h t t p s://ibb.co/Hz898r4
enter link for picture without spaces.
please help. I got the secants, chords and tangents. I think I found two angles out of the 19. I would appreciate if someone helped me get the rest of the angles.
tangent: <cde
secants:
<cbg
<agf
<abd
chord
<bd
<df
<bg
<bf
<gd
<fg
I think the first angle is 45 degrees and the sixth angle is 55 degrees.
4 answers
I assumed that 50, 100, and 140 were supposed to add to 360 so for the bottom (between g and f) I added 70 on the outside of the circle. Also, have a good night and thank you.
Ok, based on the fact that the angle subtended by a chord at the centre is twice the angle
subtended by that same chord at the circle, or the angle subtended by an arc is half the angle subtended at the centre.
We have only one circle so the same centre and radius.
So, if we assume for instance, that the central angle subtended by the chord DF = 140°
then angle#4 = 70°
work your way around, since you are given the central angles all around the circle
that is,
#3 = 35°
#4 = 70°
#14 = 50°
#11 = 50° , notice angles subtended by the same chord on a circle are equal
You can thus fill in all the angles inside the quadrilateral BGFD
Now look at #'s 2, 3, and 4. They form a straight line (180°), you have 2 of them
so #2 = 75°
Same for #'s 13, 14, and 15
You can also find the 4 angles #'s 16,17,18, and 19
e.g. #17 = 180-35-50 = 95° , etc
#5 is now easy
For #7, the angle between a tangent and a chord is equal to the angle subtended by that chord at the circle, so
#7 = 50°
which then gives you #6 = 55
Last, but not least #10 = .....
I think we got all the angles
Thankfully we are simply to LIST all the tangent lines, chords and secants
(to calculate their lengths would be a major major problem.
There is an actual relationship between arclength and chord length as seen in this
webpage:
https://www.1728.org/cntlangl.htm
subtended by that same chord at the circle, or the angle subtended by an arc is half the angle subtended at the centre.
We have only one circle so the same centre and radius.
So, if we assume for instance, that the central angle subtended by the chord DF = 140°
then angle#4 = 70°
work your way around, since you are given the central angles all around the circle
that is,
#3 = 35°
#4 = 70°
#14 = 50°
#11 = 50° , notice angles subtended by the same chord on a circle are equal
You can thus fill in all the angles inside the quadrilateral BGFD
Now look at #'s 2, 3, and 4. They form a straight line (180°), you have 2 of them
so #2 = 75°
Same for #'s 13, 14, and 15
You can also find the 4 angles #'s 16,17,18, and 19
e.g. #17 = 180-35-50 = 95° , etc
#5 is now easy
For #7, the angle between a tangent and a chord is equal to the angle subtended by that chord at the circle, so
#7 = 50°
which then gives you #6 = 55
Last, but not least #10 = .....
I think we got all the angles
Thankfully we are simply to LIST all the tangent lines, chords and secants
(to calculate their lengths would be a major major problem.
There is an actual relationship between arclength and chord length as seen in this
webpage:
https://www.1728.org/cntlangl.htm
That makes so much more sense. Thank you. My problem was figuring out which had the same measurements, as well as remembering the formulas in order to calculate the lengths. I understand a lot better now.
0 answers